Question

1.

A 250-turn solenoid with an area of 0.100m ² rotates at 40.0rad/s in a 0.0250T uniform magnetic field that is perpendicular to the axis of rotation. what is the instantaneous EMF in the solenoid at the moment that the normal to its plane is at a 30.0° angle to the magnetic field.

2.

A 4.0cm tall candle is positioned 28.0cm from thin convex lens with a 20.0cm focal length along the meter stick of an Optical Bench Kit. what is the the true statement.

	A.	The image distance is 70.0cm and image height is 10.0cm.
	B.	The image distance is 70.0cm and image height is 2.5cm.
	C.	The image distance is 120.cm and image height is 10.0cm.
	D.	The image distance is 120.cm and image height is 2.5cm.
	E.	The image distance is 120.cm and image height is 1.6cm.

Answer 1

1.

Number of turns = 250

Area= 0.100 m²

Rate of rotation (w)= 40.0 rad/s

Magnetic field (B) = 0.0250 T

Normal to the plane of solenoid is at a 30.0° angle to the magnetic field.

Therefore,

emf through the solenoid is given by:

where , Magnetic flux is given by

Thus,

2.

Object distanece (u) = 28.0 cm

Object height (H)= 4.0 cm

Focal length of the convex lens (f) = 20.0 cm

Frome lens equation we have ,

or

Now from the formula of magnification we have

or

Therefore, option (A) is correct : The image distance is 70.0cm and image height is 10.0cm